This is a simple script I use to tell when someone has highlighted me, along with mIRC's line highlighting.
Usage: mIRC will beep twice (or however many you want and however fast if you want to edit it) when someone highlight's you in a channel or PM with TEXT, an ACTION or a NOTICE.

on *:TEXT:$(* $+ $me $+ *):*:if (!$appactive) beep 2 200
on *:ACTION:$(* $+ $me $+ *):*:if (!$appactive) beep 2 200
on *!:NOTICE:$(* $+ $me $+ *):*:if (!$appactive) beep 2 200